Companion user devices, such as smartwatches, are becoming more mainstream with mobile device users. These companion user devices are generally wirelessly attached with primary user devices, e.g., smartphones, for long periods of time so that the companion user devices are able to use the cellular data services subscribed to by the primary user devices. The attachment of a companion user device to a primary user device may enable the companion user device to reduce battery consumption, as its cellular modem can be powered off. Further, by having the companion user device use the cellular data service of the primary user device, a subscriber may reduce or eliminate the apparent cellular data usage of the companion user device by having such usage counted as being accrued by the primary user device. Such reduction or elimination may enable the subscriber to minimize the cost of a cellular data subscription plan used by the companion user device.
However, companion user devices with powered-off cellular modems are generally unable to receive over-the-air (OTA) updates from wireless carrier networks. For example, an OTA update for a companion user device may be a Public Land Mobile Network (PLMN) list update to an Embedded Subscriber Identity Module (eSIM) profile that is stored in an Embedded Universal Integrated Circuit Card (eUICC) of a companion user device. Such OTA update failures may cause the companion user devices to experience various technical issues.